įurthermore, a part of the hippocampus (the ventral part in rats anterior in humans) sends outputs to the medial prefrontal cortex (mPFC) as will be discussed below, new evidence suggests that mPFC accumulates information about the context of interrelated memories. As a consequence, hippocampal processing supports the retrieval of detailed memories that constitute strong recollective experiences in humans and recollection-like memory in animals. These feedback pathways allow the hippocampus to support the retrieval of information about ‘what’ occurred based on a cue about ‘where’ an event occurred, and vice versa. Outputs of the hippocampus return to the cortical areas from which inputs arose - perirhinal–lateral entorhinal cortex, and parahippocampal–medial entorhinal cortex. Contextual representations from the ventral/anterior hippocampus are sent directly to the medial prefrontal cortex, which is positioned to influence the retrieval of specific object representations via its particularly strong connections to perirhinal and lateral entorhinal cortex. By contrast, neural ensembles in the ventral (animals) or anterior (humans) hippocampus link events within a context and strongly distinguish between different contexts. There, in the dorsal (animals) or posterior (humans) hippocampus, neural ensembles encode specific objects and the locations they occur within a context. These streams then converge in the hippocampus. Information about ‘where’ in space events occur is processed in a separate cortical stream (including posterior parietal, retrospenial, and other cortical areas) that lead into the parahippocampal and medial entorhinal cortex (green). Perceptual information about objects and events are initially processes in pathways for specific sensory modalities (vision, hearing, touch, olfaction) which project to multiple ‘association’ cortical areas (in temporal, parietal, and other cortical areas) that compose the ‘what’ stream of cortical processing that leads into perirhinal and lateral entorhinal cortex (blue). Pathways of information flow in between the hippocampus and prefrontal cortex As a natural consequence of this anatomical organization, the hippocampus is essential for forming cohesive memories of individual events within the context in which they occurred. Within the MTL, the ‘what’ and ‘where’ information streams then converge at the level of the hippocampus. In particular, the perirhinal cortex and the lateral entorhinal area are engaged by specific object stimuli and signal the familiarity of those items, whereas the parahippocampal cortex and the medial entorhinal area are involved in processing the spatial contexts in which memorable events occur. Information processed through these distinct streams is sent to the medial temporal lobe (MTL), a region critically involved in event memory. There is also a distinct stream of pathways involving several areas of the cerebral cortex that identify ‘where’ in space events occur.

We will refer to these pathways as the stream of information flow for ‘what’ we remember. Thus, multiple sensory pathways - for vision, touch, hearing, and so on - initially process information about the identity of perceptual objects and events and their outputs, and then converge onto multimodal cortical ‘association’ areas. Information about objects and events that we experience, and about the places where they occur, are processed separately in the cerebral cortex. We will begin by outlining the brain's memory system, and then focus on two key brain structures - the hippocampus and the prefrontal cortex - that support rapid encoding of new information and consolidation and organization of memory networks.Ĭonsideration of the functional anatomy of the brain system that supports memory for everyday events provides preliminary insights about how the brain encodes, organizes, and retrieves memories ( Figure 1).

Here, we will outline some of the evidence on how the brain supports these memory processes.

More recently substantial progress has been made in discovering how the brain organizes new memories into networks of knowledge that can be accessed flexibly in a range of circumstances. An enormous amount of research has led to a general understanding of how the brain forms memory traces for a novel event. Second, the brain then must consolidate the new representation in an organization that is optimized for retrieval when cued by a stimulus that may be just distantly associated to a feature of the initial experience. First, during learning, the brain must rapidly form an initial neural representation of the new experience. Our marvelous capacity to record everyday experiences and retrieve these memories much later in all manner of situations relies on two kinds of information processing.

Piaget creating memories